1. Field of the Invention
The present invention relates to a stamp cartridge utilized in a stencil-type stamp unit.
2. Description of the Related Art
Conventionally, various kinds of stamps with a print face made of rubber have been used for printing company names, addresses, or other kinds of character arrays on the surface of paper sheets. Because these kinds of stamps are usually prepared individually to each order, they are expensive and require a long period from order to delivery.
On the other hand, sheets of heat-sensitive stencil paper have been conventionally perforated using infrared radiation or a thermal head to form a desired pattern in the heat-sensitive sheets. Various patterns such as character trains, figures, or marks can be printed by transmitting ink through the perforation array.
U.S. Pat. No. 5,285,725 describes a stencil plate, or stamp cartridge, including a heat-sensitive stencil sheet and an ink-permeated body soaked with ink. This stamp cartridge is ideal for making stamps in place of conventional stamps with print faces made of rubber.
The stamp cartridge is assembled in the following way. The ink-permeated body soaked in ink is inserted in a frame so that the frame surrounds the periphery of the ink-permeated body. A synthetic resin film is adhered to one surface of the ink-permeated body and of the frame. The heat-sensitive stencil sheet is adhered to the other surface. A removable film separator may be disposed between the ink-permeated body and the stencil plate.
The stamp cartridge is attached, via a cushion material, to the lower surface of a stamp member, which includes a grip. The desired character train or other pattern is perforated in the heat-sensitive stencil sheet using infrared radiation or a thermal head. The resultant stamp includes a stamp member and a stamp cartridge and is capable of printing the desired character train or other pattern described above on sheets many times just like the usual rubber-made stamp. U.S. Pat. No. 5,463,947 describes a stamp cartridge similar to the one described in U.S. Pat. No. 5,285,725.
There also has been known a stamp cartridge 60 shown in FIG. 1. The stamp cartridge 60 includes an ink-permeated body (not shown in the drawings); a rectangular parallelepiped-shaped frame 61 whose top side is opened; and a heat-sensitive stencil sheet 62. The stamp cartridge 60 is assembled by disposing the ink-permeated body to the lower surface on the bottom wall of the frame 61 and attaching the heat-sensitive stencil sheet 62 to the frame 61 so as to cover the outer peripheral surface of the frame 61 from the lower surface of the ink-permeated body.
Adhesive is coated on the heat-sensitive stencil sheet 62. To adhere the heat-sensitive stencil sheet 62 to the outer surface of the peripheral wall of the frame 61, the heat-sensitive stencil sheet 62 is folded appropriately to form flaps 63. Also, the upper edge of the heat-sensitive stencil sheet 62 is aligned with the upper edge of the frame 61 and adhered to the peripheral wall of the frame 61 via the adhesive.
If the heat-sensitive stencil sheet 62 is adhered to the frame 61 as described above, then there is a risk that, while the stamp is being used or while being stored, capillarity may draw the ink impregnating the ink-permeated body upwards between the inner surface of the heat-sensitive stencil sheet 62 and the outer surface of the peripheral wall of the frame 61. This kind of upwardly seeping ink leaks from between the upper edge of the heat-sensitive stencil sheet 62 and the upper edge of the peripheral wall of the frame 61 to the outside of the stamp cartridge 60. As a result, ink can stain the outer surface of the heat-sensitive stencil sheet 62, which leads to staining of the characters or patterns printed by the stamp or to staining the fingers of an operator replacing the stamp cartridge 60.